With the International Technology Roadmap for Semiconductors decreasing the particle removal requirements from 125nm (0.3–0.75/cm2) in 1997 to 25nm (0.01–0.15/cm2) in 2011, an era of the most challenging cleaning applications in semiconductor manufacturing is upon us [1. Megasonic cleaning is a widely used non-contact cleaning technique. In megasonic cleaning, wafers are immersed in a cleaning liquid medium to which sonic energy is applied. High intensity sound waves generate pressure fluctuations and acoustic streaming which detach the particles from the surface and remove them. Busnaina et al[2–3 studied megasonic particle removal and the effect of acoustic streaming on the cleaning process especially in post-CMP applications. It is important to know the advantage and the limitation of megasonic cleaning technique in nano-scale particles removal.